Okmulgee County is a county in the U.S. state of Oklahoma. As of the 2020 census, the population was 36,706. The county seat is Okmulgee. Located within the Muscogee Nation Reservation, the county was created at statehood in 1907. The name Okmulgee is derived from the Hitchita word okimulgi, meaning "boiling waters".

Okmulgee is a city in and the county seat of Okmulgee County, Oklahoma, United States, and is part of the Tulsa Metropolitan Area. The name is from the Mvskoke word okimulgee, which means "boiling waters". The site was chosen because of the nearby rivers and springs. Okmulgee is 38 miles south of Tulsa and 13 miles north of Henryetta via US-75.